block/blk-wbt.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef WB_THROTTLE_H
   3 #define WB_THROTTLE_H
   4
   5 #include <linux/kernel.h>
   6 #include <linux/atomic.h>
   7 #include <linux/wait.h>
   8 #include <linux/timer.h>
   9 #include <linux/ktime.h>
  10
  11 #include "blk-stat.h"
  12
  13 enum wbt_flags {
  14         WBT_TRACKED             = 1,    /* write, tracked for throttling */
  15         WBT_READ                = 2,    /* read */
  16         WBT_KSWAPD              = 4,    /* write, from kswapd */
  17         WBT_DISCARD             = 8,    /* discard */
  18
  19         WBT_NR_BITS             = 4,    /* number of bits */
  20 };
  21
  22 enum {
  23         WBT_RWQ_BG              = 0,
  24         WBT_RWQ_KSWAPD,
  25         WBT_RWQ_DISCARD,
  26         WBT_NUM_RWQ,
  27 };
  28
  29 /*
  30  * Enable states. Either off, or on by default (done at init time),
  31  * or on through manual setup in sysfs.
  32  */
  33 enum {
  34         WBT_STATE_ON_DEFAULT    = 1,
  35         WBT_STATE_ON_MANUAL     = 2,
  36 };
  37
  38 struct rq_wait {
  39         wait_queue_head_t wait;
  40         atomic_t inflight;
  41 };
  42
  43 struct rq_wb {
  44         /*
  45          * Settings that govern how we throttle
  46          */
  47         unsigned int wb_background;             /* background writeback */
  48         unsigned int wb_normal;                 /* normal writeback */
  49         unsigned int wb_max;                    /* max throughput writeback */
  50         int scale_step;
  51         bool scaled_max;
  52
  53         short enable_state;                     /* WBT_STATE_* */
  54
  55         /*
  56          * Number of consecutive periods where we don't have enough
  57          * information to make a firm scale up/down decision.
  58          */
  59         unsigned int unknown_cnt;
  60
  61         u64 win_nsec;                           /* default window size */
  62         u64 cur_win_nsec;                       /* current window size */
  63
  64         struct blk_stat_callback *cb;
  65
  66         u64 sync_issue;
  67         void *sync_cookie;
  68
  69         unsigned int wc;
  70         unsigned int queue_depth;
  71
  72         unsigned long last_issue;               /* last non-throttled issue */
  73         unsigned long last_comp;                /* last non-throttled comp */
  74         unsigned long min_lat_nsec;
  75         struct request_queue *queue;
  76         struct rq_wait rq_wait[WBT_NUM_RWQ];
  77 };
  78
  79 static inline unsigned int wbt_inflight(struct rq_wb *rwb)
  80 {
  81         unsigned int i, ret = 0;
  82
  83         for (i = 0; i < WBT_NUM_RWQ; i++)
  84                 ret += atomic_read(&rwb->rq_wait[i].inflight);
  85
  86         return ret;
  87 }
  88
  89 #ifdef CONFIG_BLK_WBT
  90
  91 static inline void wbt_track(struct request *rq, enum wbt_flags flags)
  92 {
  93         rq->wbt_flags |= flags;
  94 }
  95
  96 void __wbt_done(struct rq_wb *, enum wbt_flags);
  97 void wbt_done(struct rq_wb *, struct request *);
  98 enum wbt_flags wbt_wait(struct rq_wb *, struct bio *, spinlock_t *);
  99 int wbt_init(struct request_queue *);
 100 void wbt_exit(struct request_queue *);
 101 void wbt_update_limits(struct rq_wb *);
 102 void wbt_requeue(struct rq_wb *, struct request *);
 103 void wbt_issue(struct rq_wb *, struct request *);
 104 void wbt_disable_default(struct request_queue *);
 105 void wbt_enable_default(struct request_queue *);
 106
 107 void wbt_set_queue_depth(struct rq_wb *, unsigned int);
 108 void wbt_set_write_cache(struct rq_wb *, bool);
 109
 110 u64 wbt_default_latency_nsec(struct request_queue *);
 111
 112 #else
 113
 114 static inline void wbt_track(struct request *rq, enum wbt_flags flags)
 115 {
 116 }
 117 static inline void __wbt_done(struct rq_wb *rwb, enum wbt_flags flags)
 118 {
 119 }
 120 static inline void wbt_done(struct rq_wb *rwb, struct request *rq)
 121 {
 122 }
 123 static inline enum wbt_flags wbt_wait(struct rq_wb *rwb, struct bio *bio,
 124                                       spinlock_t *lock)
 125 {
 126         return 0;
 127 }
 128 static inline int wbt_init(struct request_queue *q)
 129 {
 130         return -EINVAL;
 131 }
 132 static inline void wbt_exit(struct request_queue *q)
 133 {
 134 }
 135 static inline void wbt_update_limits(struct rq_wb *rwb)
 136 {
 137 }
 138 static inline void wbt_requeue(struct rq_wb *rwb, struct request *rq)
 139 {
 140 }
 141 static inline void wbt_issue(struct rq_wb *rwb, struct request *rq)
 142 {
 143 }
 144 static inline void wbt_disable_default(struct request_queue *q)
 145 {
 146 }
 147 static inline void wbt_enable_default(struct request_queue *q)
 148 {
 149 }
 150 static inline void wbt_set_queue_depth(struct rq_wb *rwb, unsigned int depth)
 151 {
 152 }
 153 static inline void wbt_set_write_cache(struct rq_wb *rwb, bool wc)
 154 {
 155 }
 156 static inline u64 wbt_default_latency_nsec(struct request_queue *q)
 157 {
 158         return 0;
 159 }
 160
 161 #endif /* CONFIG_BLK_WBT */
 162
 163 #endif